mount, s3: clarify allowOthers requirement and bucket name error (#12197)

* mount, s3: clarify allowOthers requirement and bucket name error

`weed mount -allowOthers` defaults to true. On Linux, a non-root
user's mount then needs `user_allow_other` in /etc/fuse.conf, but the
help text only said "allows other users to access the file system".
Say so in the help, and point at -allowOthers=false.

Also fix the grammar of the bucket name length error ("must between
[3, 63]" -> "must be between 3 and 63").

Help and error text only; no behaviour change.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* s3: normalize the remaining VerifyS3BucketName error messages

The length message was clarified; the rest of the function still had
inconsistent phrasing ("name must start", "cannot be ip addresses",
"prefix xn-- ... in bucket prefix"). Align them on "bucket name ..."
wording matching the AWS bucket naming rules.

---------

Co-authored-by: pingqiu <pingqiu999@gmail.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: user.email <chrislusf@users.noreply.github.com>

weed/command/mount.go

@@ -115,7 +115,7 @@ func init() {
 	mountOptions.cacheMetaTtlSec = cmdMount.Flag.Int("cacheMetaTtlSec", 60, "metadata cache validity seconds")
 	mountOptions.cacheDirMaxEntries = cmdMount.Flag.Int("cacheDirMaxEntries", 100000, "a directory with more children than this is not cached locally but read directly from the filer; 0 caches everything")
 	mountOptions.dataCenter = cmdMount.Flag.String("dataCenter", "", "prefer to write to the data center")
-	mountOptions.allowOthers = cmdMount.Flag.Bool("allowOthers", true, "allows other users to access the file system")
+	mountOptions.allowOthers = cmdMount.Flag.Bool("allowOthers", true, "allows other users to access the file system; on Linux, when mounting as a non-root user, this requires 'user_allow_other' in /etc/fuse.conf, so set -allowOthers=false otherwise")
 	mountOptions.defaultPermissions = cmdMount.Flag.Bool("defaultPermissions", true, "enforce permissions by the operating system")
 	mountOptions.umaskString = cmdMount.Flag.String("umask", "022", "octal umask, e.g., 022, 0111")
 	mountOptions.nonempty = cmdMount.Flag.Bool("nonempty", false, "allows the mounting over a non-empty directory")